1. Field of the Invention
The present invention is directed to a catheter which can be located in a patient using a non-ionizing field, such as an electromagnetic or acoustic field, and to a method for locating such a catheter.
2. Description of the Prior Art
In angiographic examinations, and in particular in those using invasive techniques, a so-called pathfinder illustration is frequently used in combination with an x-ray transillumination. For identifying the exact topology of a vessel region of interest (vessel structure or vessel architecture) using a contrast agent, the x-ray image of the vessel structure is first acquired and stored. In the subsequent employment of a catheter, the catheter is portrayed in the transillumination images in which the vessels are not visible. The transillumination image sequences which reproduce the position, orientation and movement of the catheter are thus constantly combined (superimposed) with the contrast agent image which contains the vessel structure. The resulting overall sequences accordingly show the catheter within the vessel architecture, and thus allow a controlled motion by the physician.
This technique requires the use of a transillumination means both in the contrast agent injection for generating the stored image of the vessel architecture, and during the subsequent catheter employment. This means the patient and the physician must be subjected to a radiation exposure beyond that which would be required only for producing the stored image of the vessel architecture.
There is no reasonable substitute for the use of x-ray imaging with a contrast agent via a catheter for acquiring and storing images of the vessel architecture. The exposure ensues once, before the subsequent catheter employment. Such imaging requires only a low radiation exposure for the patient and the physician.